Edward Stratemeyer published The Bobbsey Twins: or, Merry Days Indoors and Out,
in 1904, using the psuedonym Laura Lee Hope. Although most collectable copies of
this book were published by Grosset and Dunlap, and the more desirable (meaning older)
copies bear the full applique cover, these are not the original. Look inside an old
G&D of Volume 1 and you will see the original copyright attribution to "Mershon."
Find an original "Mershon Bobbsey" and your next stop (unless you want
to keep it) is Sotheby's Auction House! "Mershon Bobbseys" are rare, collectable,
and valuable. Less than a dozen are known to have survived. Here's what you will
be looking for (the book is smaller than the Grosset and Dunlap issues that
we are all used to):
The 1907 Chatterton-Peck Bobbsey Twins in the Country
The second and third books in the series are attributed to Chatterton-Peck, a company
that was formed after the Mershon Company. There are apparently no surviving Chatterton-Peck
"Bobbsey Twins at the Seashore" and in fact none may have been printed.
The Chatterton-Peck "Bobbsey Twins in the Country" is also very rare. A
copy was recently auctioned on ebay for $305.
The books you are looking for will be smaller than the current Grosset and Dunlap
issues, so keep that in mind.